Digital Resources
Astronomical Pseudo-Science
Periodic Table
Picture of the Day
Hubble Space Telescope
Chandra X-ray Observatory
Sky and Telescope
Astronomy Magazine
Local Weather
Search the Web

Animations
Cosmic Microwave Background
Map of the Universe
Galaxy Evolution
Black Holes
Lunation
Lunar Phases
Synchronous Rotation
Retrograde Motion
Kepler's Laws
Newton's Laws

Check out: astronomycenter.org - digital resources for astronomy education. Students and teachers can search and browse a library of online resources all about college-level introductory astronomy. This site will be brought to you by West Chester University, the American Astronomical Society, the National Science Digital Library and the National Science Foundation. For now, try out some of the sites and animations at left.

Physics: These Java applets from the PhET tema at the University of Colorado will help you visualize the physics of heat, matter, energy and light.

1. Electromagnetic fields: http://phet.colorado.edu/simulations/emf/emf.jnlp
2. Energy Skate Park: http://phet.colorado.edu/simulations/energyconservation/energyconservation.jnlp
3. Discharge Lamps: http://phet.colorado.edu/simulations/dischargelamps/dischargelamps.jnlp
4. Hydrogen Atom: http://www.colorado.edu/physics/phet/dev/hydrogen-atom/1.00.00/hydrogen-atom.jnlp
5. My Solar System: http://phet.colorado.edu/simulations/orbits/orbits.swf
6. Gas Properties: http://phet.colorado.edu/simulations/gasses-buoyancy/idealgas.jnlp
7. Blackbody Spectrum: http://phet.colorado.edu/simulations/blackbody/blackbody.swf
8. Photoelectric effect: http://phet.colorado.edu/simulations/photoelectric/photoelectric.jnlp

Black Holes: See black hole animations by Robert Nemiroff and others.

Dark Matter: check out this lecture on Dark Matter by James Schombert at the University of Oregon. Click on the "Display Quiz #16" button at the bottom to test your knowledge.

Dark Energy: please read this space.com article about evidence for dark energy from the dynamics in the local group of galaxies. Also, view this computer simulation.

Cosmic Microwave Background Worksheet

General Astronomy, ESS 111, Lab Activity - Week of April 19, 2004

Background Reading

The NASA satellite named the Wilkinson Anisotropy Probe is currently taking the most detailed measurements to date of the Cosmic Microwave Background. Their website has one of the best introductions around to Big Bang Theory and the CMB.

What to do…

Grab your laptop from the cart and login to the wireless LAN using your username (e.g., ab123456) and password. If you do not have one, please use your lab partner's. Get a username and password from the ACC student help desk in Anderson 20.

What to read…

http://map.gsfc.nasa.gov/m_uni.html
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest3.html
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest1.html
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest2.html

Questions…

1. Using the Hubble constant you measured in lab last week, approximately how old is the Universe today?

2. As we look at light at larger and larger redshift, what can you say about the stuff (matter) that emitted the light? When was this light emitted?

3. It is believed that the stuff that emitted the Cosmic Microwave Background did so when the universe was only about 400,000 years old. Describe the physical conditions (temperature, density, state of matter, composition) in the universe at that time.

4. Why did the universe suddenly become transparent at around t = 380,000 years, allowing the radiation to flow out into space?

5. Assuming the universe's temperature was about T = 3,000 K when the CMB was emitted and that the temperature of the CMB today is T₀ = 2.725 K, calculate the redshift, z, of the CMB. Hint: T₀/T = 1/z.

6. How fast is the CMB receding away from us? Hint: v = cz/(z+1) where the speed of light c = 300,000 km/s.

7. The CMB is remarkably smooth: its temperature is nearly the same in all directions. What does this tell us about the early universe?

8. The CMB is one of the three pillars of the Big Bang Theory. Why does its discovery provide strong support for the Big Bang Theory?